In semiconductor processing, semiconductor-on-insulator (SOI) technology is becoming increasingly important since it permits the formation of high-speed integrated circuits (ICs). In SOI technology, a buried insulating layer, typically an oxide, electrically isolates a top semiconductor layer from a bottom semiconductor layer. The top semiconductor layer, which is often referred to as the SOI layer, is generally the area of the SOI substrate in which active semiconductor device such as, for example, field effect transistors and/or bipolar devices, are built.
Devices formed using SOI technology offer many advantages over the bulk semiconductor counterparts including, for example, higher performance, absence of latch-up, higher packaging density and low voltage applications. More specifically, devices built on SOI substrates have lower parasitic capacitance and leakage current than those that are built on bulk semiconductor substrates. Lower capacitance and leakage current generally provide for devices that operate at faster speeds and lower standby power.
However, SOI substrates have floating body effects and hence body contacts are generally needed on critical devices that cannot tolerate varying body voltage, resulting in a significant device density penalty. Also, SOI substrates are much more expensive than their bulk counterparts because of complex processing and difficult quality control. Typically, SOI substrates are made by a layer transfer process or by an ion implantation process such as SIMOX (Separation by Ion Implantation of Oxygen).
In view of the above, there is still a need to provide new and improved substrate materials that have all the advantages of SOI substrates, yet overcome the floating body effects observed in prior art SOI substrate without requiring a separate body contact.